Haroon Qureshi
139a5b6494
PiperOrigin-RevId: 838701951 Change-Id: I339eafd35d919710cb47bb04e9a8e29f92739513
95 lines
3.3 KiB
C++
95 lines
3.3 KiB
C++
// Copyright 2025 DeepMind Technologies Limited
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef MUJOCO_SRC_EXPERIMENTAL_PLATFORM_SIM_HISTORY_H_
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#define MUJOCO_SRC_EXPERIMENTAL_PLATFORM_SIM_HISTORY_H_
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#include <span>
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#include <vector>
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#include <mujoco/mujoco.h>
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namespace mujoco::platform {
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// A historical buffer of simulation data.
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class SimHistory {
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public:
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SimHistory() = default;
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// Simulation data is stored a an array of mjtNum; see mj_getState().
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using State = std::vector<mjtNum>;
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// Clears and initializes the history buffer to store state.
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void Init(int state_size, int max_history = 2000, int max_bytes = 1e8);
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// Adds an uninitialized state to the history and returns a reference to it
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// so that the caller can populate the data. Also resets the current index to
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// 0; see SetIndex() for details.
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std::span<mjtNum> AddToHistory();
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// Returns the history at the given index (i.e. the number of steps) in the
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// past. The `offset` will be clamped internally to the range [0, Size() - 1].
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// This function returns the valid, clamped value.
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//
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// For example, calling SetIndex(0) will return the most recently recorded
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// state. Calling SetIndex(-N) will return the state from N steps ago.
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//
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// Note that future calls to `AddToHistory` will begin recording from the
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// newly set index, effectively creating a new "branch" of the history buffer.
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// If you do not want to lose any states, you must call `SetIndex(0)` before
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// before resuming playback.
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//
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// For example, consider you have recorded 6 states:
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// N(-5) N(-4) N(-3) N(-2) N(-1) N(0)
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// -----------------------------------------^
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//
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// You then call `SetIndex(-3)`:
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// N(-5) N(-4) N(-3) N(-2) N(-1) N(0)
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// ------------------^
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//
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// And then call `AddToHistory()
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// N(-5) N(-4) N(-3) N(-2) N(-1) N(0)
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// | | | x x x
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// v v v
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// N'(-3) N'(-2) N'(-1) N'(0)
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// -------------------------^
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//
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// In this case, we effectively erase states 0 to -3 of the previous history,
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// "copy" the older states into the new branch, and add the most recent state
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// at the "head" of the history buffer.
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std::span<mjtNum> SetIndex(int offset);
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// Returns the currently set index.
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int GetIndex() const { return offset_; }
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// Returns the number of states in the history buffer.
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int Size() const { return size_; }
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private:
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// The history of states.
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std::vector<State> history_;
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// The index at which the next AddToHistory() call will write.
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int cursor_ = 0;
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// The most recently requested offset from SetIndex().
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int offset_ = 0;
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// The total number of states available in the history buffer.
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int size_ = 0;
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};
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} // namespace mujoco::platform
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#endif // MUJOCO_SRC_EXPERIMENTAL_PLATFORM_SIM_HISTORY_H_
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